1. Field of the Invention
The present invention relates to in-vehicle devices, and more particularly relates to a car navigation system equipped with a speech-recognition function.
2. Description of the Related Art
Car navigation systems employing GPS (Global Positioning System) have been widely used. This car navigation system includes a display unit (monitor) for displaying map information and the like, a main unit for containing a computation processing unit and the like therein, a remote control unit for inputting control information into the car navigation system, and the like.
Recently, a car navigation system provided with a speech input device having a speech-recognition function as a device for inputting control information into the navigation system other than the remote control unit has come into use. This car navigation system provided with this speech input device includes a speech input microphone. Conventionally, this microphone has been installed on, for example, an in-vehicle dashboard, a steering column, a sun visor, an A pillar unit, or the like, and it is connected to a microphone cable led from the main unit of the car navigation system.
The main units of car navigation systems are often provided in trunks instead of the cabins. Accordingly, in the car navigation device provided with the speech input device, the microphone cable is led from the trunk and is connected to the microphone on the dashboard or the like inside the cabin. This requires the length of the microphone cable to be as long as 7 m. This also makes the wiring work for the microphone cable complicated.
Providing a noise microphone for inputting a noise signal thereinto, in addition to the speech input microphone, in the speech input device of the car navigation system is proposed and comes into practical use. A signal that is input into the speech input microphone is a mixture of the speech signal and the noise signal. A signal that is input into the noise microphone is primarily the noise signal. By subtracting the signal captured from the noise microphone from the signal captured from the speech input microphone, only the speech signal can be extracted. However, the provision of the two microphones, i.e. the speech input microphone and the noise microphone is disadvantageous in terms of the cost. Therefore, it is desirable that a preferable S/N (signal to noise) ratio is realized using a single microphone.
The speech input device for solving such a problem is disclosed in Japanese Unexamined Patent Application Publication No. 10-11084. This publication is characterized in that the speech input device of an in-vehicle navigation system includes a navigation wireless remote control unit for performing remote control and the microphone for inputting the speech into the speech input device so that the input speech is controlled using the speech recognition wherein the microphone is provided in the navigation wireless remote control unit. Since the microphone is disposed in the wireless remote control unit for inputting a control signal of the car navigation system into the navigation system, no wiring work for the microphone cable is required. In addition, when a user inputs the speech into the microphone, one can speak into the microphone incorporated in the remote control unit while having one""s mouth close to the remote control unit. Therefore, less noise influences input of the speech.
As described above, the speech input device disclosed in this publication capable of solving the conventional problem is useful.
However, the user must hold this wireless remote control unit in order to input the speech into the microphone incorporated in the wireless remote control unit. When the user inputs the speech while driving, the speech input may interfere with the driving operation.
Accordingly, it is an object of the present invention to provide an in-vehicle device, particularly, a car navigation system which does not require a long cable for a microphone and which requires no or simple microphone cable wiring work. It is another object of the present invention to provide the in-vehicle device, particularly, the car navigation system which prevents the speech input from interfering with the driving operation.
To this end, according to a first aspect of the present invention, there is provided an in-vehicle device capable of performing control by means of speech recognition, including a monitor for displaying map and other information and a speech input microphone connected to the monitor.
The present invention is made by noting use of the monitor as an object to have a microphone cable led from the monitor. In the in-vehicle device, the monitor is normally disposed on a dashboard. Therefore, when the microphone cable is led from the monitor and the microphone is installed on, for example, the dashboard, the cable wiring becomes simple and the length required for the cable wiring becomes shorter. In addition, since the microphone led from the monitor may be installed on, apart from the dashboard, a conventional part such as a steering column, a sun visor, or an A pillar unit, a user does not have to hold the microphone.
It is possible to even eliminate the microphone cable itself. The foregoing problem can be solved by integrating the microphone in the enclosure constituting the monitor. In this case, since there is no microphone cable, the wiring work is not necessary. In addition, since the microphone cable is not exposed in the cabin, there is no risk in that the exposed cable spoils the appearance.
The microphone may be connected to the monitor directly or via a cable. According to the form in which the microphone is connected via the cable to the monitor, the amount of wiring work is considerably decreased compared to a conventional case in which the cable is wired from the trunk to the front part of the cabin. The length of the cable required for wiring is considerably decreased compared to the conventional case. According to the form in which the microphone is directly connected to the monitor, the necessity of the wiring is eliminated. Due to the lack of cable wiring in the cabin, exposed microphone cable is prevented and the appearance remains unspoiled.
When the microphone is installed via the cable on the monitor, the installation part of the monitor is arbitrary. That is, it may be installed on a conventional part such as the dashboard, the steering column, the sun visor, and the A pillar unit.
When the microphone is directly installed on the monitor, the microphone may be installed on the outside of an enclosure of the monitor, or the microphone may be installed on the inside of the enclosure of the monitor.
The number of the microphones connected to the monitor may be one or more than one. In addition, the cable or the microphone may be connected so as to be attachable to the monitor. When the microphone is connected to the monitor, the microphone may be fixed to the monitor. The microphone may be connected to the monitor in such a manner that the orientation of the microphone is adjustable. This is because it is desirable that the optimum orientation of the directivity axis of the microphone be set for each speaker. A method for altering the direction of the microphone is performed manually or by means of a driving source such as a motor.
A typical application of the in-vehicle device according to the present invention is a car navigation system. According to a second aspect of the present invention, a car navigation system includes a recognizing unit for recognizing input speech, a monitor for displaying a recognition result from the recognizing unit, and a microphone, integrally connected to the monitor, for inputting the speech. The present invention may be applied to other in-vehicle devices, such as a car audio system.
In the vehicle, other than speech for the speech recognition, noise such as a sound of an engine is input into the microphone. Accordingly, a noise-reducing unit for reducing a noise input from the microphone may be provided in the car navigation system. A wide variety of known noise-reducing units may be applied to this noise-reducing unit. When the microphone is directly connected to the monitor, a diffraction effect of the entire monitor improves the sensitivity of the microphone, which prevents the noise. Therefore, in this case, the monitor serves as the noise reducing unit.
Conventionally, independent of the microphone for speech, a microphone for capturing the noise has been provided as the noise-reducing unit. In the present invention, the microphone for speech is provided on one of the front and the rear faces of the monitor while the microphone for noise is provided on the other face. That is, according to a third aspect of the present invention, a monitor device includes a monitor main body for displaying map and other information, a speech input microphone provided on one of the front and rear faces of the monitor main body, and a noise input microphone provided on the other face of the monitor main body. The microphone for noise serves as the noise-reducing unit and is characterized in that the microphone for the noise is disposed on one face of the monitor which is the opposite face of the monitor on which the microphone for speech is disposed.
Further advantages of the present invention become apparent from the following description of the preferred embodiments.